Mechanical key interlock



Jan. 30, 1968' A. SCHONFELD ET L 3,366,216

MECHANICAL INTERLOCK Filed Aug. 30, 1965 I 18 54 2 PM if/ WW INVENTORS ARNOLD SCH ELD MARVIN JA AGENT United States Patent 3,366,216 MECHANICAL KEY INTERLOCK Arnold Schonfeld, Levittown, and Marvin Jacoby, Fort Washington, Pa., assignors to Sperry Rand Corporation, New York, N.Y., a corporation of Delaware Filed Aug. 30, 1965, Ser. No. 483,715 Claims. (Cl. 197-107) ABSTRACT OF THE DISCLOSURE A key interlock which utilizes a leaf spring formed in a serpentine shape is disclosed. The spring is located in a channel whose length is slightly longer than the spring length. The hills of the spring are positioned under the keys and are flattened by the actuation of the keys.

This invention relates to keylocks but more specifically to an interlock for preventing depression of more than one key at a time in a keyboard.

While devices for his purpose are well known in the keyboard art, because of their expense and complexity they have not become popular.

Therefore, it is the primary object of this invention to provide an improved keylock for keyboards which prevents the depression of more than one key at a time, and which is characterized by its simple construction and low cost.

In accordance with the above and first briefly described, the invention comprises an elongated thin leaf spring formed in a serpentine shape with alternate hills and valleys. The spring is confined in a channel under a row or column of keys with the hills directly beneath the underside of the keys. The channel confines the spring with sufiicient flexibility only to permit one key in the row to be depressed. In another form of the invention wherein a plurality of key rows are provided, serpentine springs are utilized in an arrangement permitting only one key at a time in the Whole keyboard to be depressed.

In the drawings:

FIGURE 1 is a sectional view through a row of keys incorporating the invention;

FIGURE 2 is a sectional view taken along line 2-2 of FIGURE 1; and

FIGURE 3 is a somewhat diagrammatic view illustrating the invention as used in a multi-row keyboard.

As seen in FIGURE 1 a row of keys 10 are mounted with their stems 12 extending through a base plate 14. Shaking under the keys in a channel 16 formed in the base plate is a spring 18 formed from an elongated flat thin spring leaf into serpentine shape with alternate hills and valleys 20 and 22 respectively, one hill under each key. Preferably, the spring passes along the sides of the stems 12, as seen in FIGURE 2, but this is a matter of choice.

One end of the spring-the right end 24 as shown here by way of example-preferably is anchored against the right end wall 26 of the channel 16 with its other end 28 spaced from the opposite end wall 30 a distance X. This space is sufiicient to permit the spring to elongate only in response to the flattening of one hill 20 by the depression of one key the amount necessary to actuate its associated apparatus (not shown). The distance X may also be adjusted by providing a screw 29 in wall 30 at the end of each key row. If more than one key is depressed simultaneously, neither c-an be depressed sufficiently to actuate its associated apparatus before the left end 28 of the spring 18 contacts wall 30 and locks the keys against further depression.

As the spring elongates, the hills 20 to the left of the depressed key, if any, move to the left in contact with the underside of the keys which are prevented from lifting by the pins 32 extending through their stems 12 in contact with the underside of plate 14. If the leftmost key is depressed, only its hill is effected. It flattens until end 28 contacts wall 30. The ends of the spring may be turned upwardly, as shown, or downward, to provide a bearing surface for contact with the end walls 26 and 30. A cover plate 34 is provided over channel 16 for decorative purposes.

It will be realized, of course, that the spring 18 can also serve to hold the keys in their normal inoperative positions. If desired, the keys may be urged to an inoperative position just above and out of contact with the hills 20 by other means, such as additional spring means, not shown. In this case, the cover plate 34, as seen at 35 in FIGURE 2, serves to define the upper limits of the hills.

As shown diagrammatically in FIGURE 3 the ends 24 of the serpentine springs 18 of a plurality of key rows, such as described above, are anchored against one wall while their other ends 28 bear against the hills 41 of a similar spring 42 confined in a channel 44 traversing the other ends. The length of channel 44 is sufiiciently longer-41y X dimension-than the spring 42 to permit the spring to elongate only in response to the elongation of one of the springs 18 by one key, as described above, at which time its ends 46 and 48 are abutting the end walls 50 and 52 of the channel locking the rest of the keys against actuation. Thus only one key at a time in the whole keyboard can be depressed sufliciently to actuate its associated apparatus.

It will be understood that the use of the word key throughout, is intended to encompass its broad as well as its narrow meaning. For example, in its broad sense, it would include interconnected link-s such as are commonly employed in typewriter keyboards, and which as a result of key operation would bear against the spring hills 20'.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A mechanical key interlock comprising:

(A) a base structure having an elongated channel of finite length formed in its top surface;

(B) a plurality of keys;

(C) means arranging said keys over said channel; and

(D) an elongated spring member formed into serpentine shape with alternate hills and valleys, said member being positioned within said channel with its hills beneath said keys and its valleys resting on the bottom of said channel;

(E) said spring member being equal in length to said channel minus a distance X, wherein X is equal to the elongation of said spring member by the flattening of a hill in response to the depression of only one of said keys a distance sufiicient to actuate its associated apparatus.

2. A key interlock according to claim 1 wherein:

(A) the hills of said serpentine spring are in contact with the underside of said keys; and further includes (B) means to prevent the other of said keys being lifted by said spring upon depression of a key.

3. A key interlock according to claim 1 wherein:

(A) said means for arranging said keys comprises,

(1) a stem for each key, and

(2) each stem extends through said channel into said base structure with one end attached to said key.

4. A key interlock according to claim 2 wherein:

(A) the means of claim 2 comprises abutment means on each of said keys arranged to abut cooperating portions of said base structure.

5. A key interlock in accordance with claim 3, where- (A) said serpentine spring is positioned along the sides of said stems in said channel.

6. A key interlock according to claim 1 wherein:

(A) said serpentine spring is a thin elongated leaf spring.

7. A mechanical key interlock according to claim 1 vherein:

(A) the means for arranging said keys comprises,

(1) a stern for each key, and (2) each stern extends through said channel and said base structure;

(B) the serpentine spring member is a thin spring leaf positioned in said channel along the sides of said stems with its hills in contact with the undersides of said keys; and

(C) said stems are provided with abutment means arranged to contact the underside of said base structure in a manner preventing said spring member from lifting other of said keys upon the depression of one.

8. A key interlock according to claim 1 and further ineluding:

(A) means for adjusting the X distance.

9. A mechanical key interlock for keyboards, comprising:

(A) a base structure;

(B) a plurality of keys;

(C) means supporting said keys spaced above said base structure in a plurality of rows;

(D) a first elongated spring member of serpentine shape with alternate hills and valleys, positioned under each row of keys with a hill under each key and its valleys resting on said base structure;

(E) another similar serpentine spring member traversing the ends of each row of keys along one side of said keyboard with its hills aligned with and facing the key rows and its valleys resting against and butting said base structure;

(F) means anchoring one end of each spring on one side of each row of keys with their other ends bearing against the hills of said traversing spring member; and

(G) means preventing elongation of said traversing spring by more than a distance X, wherein X is equal to the elongation of said traversing spring by the flattening of one of its hills by the elongation of one of said first spring members upon depression of only one key a sufficient distance to actuate its associated apparatus.

10. A key interlock according to claim 9, wherein:

(A) said base structure is provided with an elongated first channel under each key row in which said first spring members are positioned with their hills in contact with the undersides of said keys, and a second channel traversing and in open communication with the ends of said first channels and in which said traversing spring member is positioned with one of its hills aligned with and facing each of said first channels and its valleys against a side wall of said second channel.

References Cited UNITED STATES PATENTS 1,880,896 10/1932 Doughty 19798 2,060,431 11/1936 Spicer 197-107 X 3,032,168 5/1962 Reynard 197107 3,107,771 11/1963 Debus 197-107 FOREIGN PATENTS 15,468 1914 Great Britain.

ROBERT E. PULFREY, Primary Examiner.

E. T. WRIGHT, Examiner. 

